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Annual Biennial

Cosmos sulphureus
  • RHS Plants for pollinators

yellow cosmos

C. sulphureus is a half-hardy annual with fresh, fern-like foliage and a long flowering season. Selections are variable in height, most between 50cm and 1m, but including some dwarf forms. Flower colour is varied, in many tones of yellow, orange and red

Synonyms
Bidens sulphurea
Size
Ultimate height
0.1–0.5 metres
Time to ultimate height
1 year
Ultimate spread
0.1–0.5 metres
Growing conditions
Chalk
Loam
Sand
Moisture
Moist but well–drained
pH
Acid, Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Green
Summer Orange Red Yellow Green
Autumn Orange Red Yellow Green
Winter
Position
  • Full sun
Aspect

West–facing or South–facing

Exposure
Sheltered
Hardiness
H3
Botanical details
Family
Asteraceae
Native to the UK
No
Foliage
Deciduous
Habit
Bushy, Columnar upright
Genus

Cosmos can be annuals or perennials with simple or pinnately divided leaves and large, long-stalked daisy-like flowers in summer

Name status

Correct

Plant range
Mexico, C America, N S America

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How to grow

Cultivation

Grow in moderately fertile, moist but well-drained soil in full sun

Propagation

Propagate by seed in mid spring

Suggested planting locations and garden types
  • Cottage and informal garden
  • City and courtyard gardens
  • Sub-tropical
  • Cut flowers
  • Flower borders and beds
Pruning

Deadheading should be carried out regularly to prolong flowering

Pests

Aphids and slugs may be a nuisance

Diseases

Grey moulds may be a problem

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